It has been proposed in U.S. patent application Ser. No. 08/862,708 filed May 23, 1997 to utilize biaxially oriented polyolefin sheet laminated to cellulose photographic grade paper for use as a silver halide color photographic base in order to provide a more effective layer between the photosensitive layers and the base paper, in particular, to more effectively incorporate colorant materials, enhance sharpness, improve gloss, reduce humidity curl, and improve whiteness, as well as provide an improved smooth surface.
This superior invention to traditional photographic support can be further enhanced to reduce discoloration and fading of the silver halide dye image and discoloration of white areas in silver halide color photographic base in the presence of light by the addition of an oxygen barrier to prevent oxygen from being transmitted through the base structure to the dye image and white areas. Such an enhancement in traditional photographic support was addressed in U.S. Pat. No. 5,391,473 (Lacz et al) and U.S. Pat. No. 4,283,486 (Aono et al) where it was taught that oxygen is responsible for discoloration and fading of the silver halide dye image and discoloration of white areas in silver halide color photographic base in the presence of light. In addition, European Patent Application EP 0 803 377 A1 (Ogata et al) discusses the desirability of an oxygen barrier layer for recording applications such as thermal imaging for preventing fade.
The cause of the discoloration and fading of the dye image and discoloration of the white area is considered to be caused mainly by a combination of high intensity light and the presence of oxygen. Therefore techniques for preventing oxygen from coming in contact with the die images for traditional silver halide color photographic structures have been proposed. For example, techniques are described in Research Disclosure, No. 15162, page 82 (November 1976), and Japanese Patent Application (OPI) Nos. 11330/74 and 57223/75 wherein an oxygen-shielding layer formed from a substance having a low oxygen permeability is used to cover the dye images.
Therefore, it is desirable to incorporate an oxygen barrier in the biaxially oriented polyolefin sheet laminated to cellulose photographic grade paper for use as a silver halide color photographic base. The teachings listed above for traditional imaging supports help to identify what types of materials could reduce the fade and discoloration problem; however, incorporation of these materials into the biaxially-oriented-polyolefin-sheet-laminated-to-cellulose--photographic-g rade-paper structure is not trivial. What remains is a need for an oxygen barrier incorporated into the structure between the paper and the upper surface layer of said biaxially oriented polyolefin sheet, which has no detrimental effect on the robust bond between the oriented sheets and the base paper.